The present invention generally relates to screeds for leveling a concrete pour, and more particularly to a motorized, vibrating screed with rollers.
As is well known in the construction industry, many multi-story buildings are fabricated with composite decks. A composite deck is generally formed by the integrated combination of concrete and structural steel. Typically, multi-story buildings are formed with horizontal and vertical steel support beams and composite decks. The composite deck is formed by initially placing corrugated sheet metal decking across the top surfaces of the horizontal support beams wherein the deck is to be placed. Next generally elongate, vertical studs (Nelson studs) are welded to the corrugated sheet metal in linear alignment with the horizontal support beams such that the studs extend vertically upward from the top, horizontal surface of the structural beams to which they are attached. In this respect, the lower end of the Nelson stud is abutted against the upper surface of the metal decking in a position approximately above the longitudinal axis of the beam. Since the metal decking has a relatively thin cross-section, the welding procedure is operable to form an integral connection between the Nelson stud, metal decking and top surface of the beam. Concrete reinforcement material such as rebar or wire mesh is then placed over the top surface of the corrugated deck. Typically, the reinforcement material is supported by "chairs" to place the reinforcement material a prescribed distance above the deck's top surface. Concrete is then poured upon the upper surface of the corrugated sheet metal decking in a manner such that the concrete completely surrounds the exposed portions of each of the Nelson studs and the concrete reinforcement material. The interconnection of the structural steel beams, the corrugated sheet metal decking, the Nelson studs, the concrete reinforcement material and the concrete pour form the composite deck structure.
In composite deck construction, a certain concrete thickness is specified for the concrete poured upon the metal decking. The concrete thickness throughout the entire surface area of the composite deck must be uniform, thereby necessitating that the pour be leveled in a manner achieving such a uniform thickness. The leveling device used to level concrete pours is referred to as a screed. Typically, the screed is an elongate, section of material having a straight edge that is drawn over the concrete pour. In composite deck construction, the screed extends between and is supported by a pair of screed rails positioned at a prescribed height above the corrugated metal decking. The screed is supported by a pair of tabs that extend outwardly from the screed and rest upon a top surface of the screed rails. The screed rails support the screed at a prescribed uniform height above the metal decking such that the straight edge of the screed will level the concrete pour as the screed is being drawn along the length of the screed rails. Typically, the screed rails are placed upon adjacent, parallel support beams in a manner wherein each screed rail is generally parallel to the support beam to which it is attached.
The screed rails are attached to the support beams through the use of screed post assemblies. Typical screed post assemblies comprise a screed pad with a screed post extending upwardly therefrom. The screed pad must be anchored to the corrugated sheet metal decking by means of screws and/or adhesives. Once the screed pad is anchored to the metal decking, the screed post is threadably connected to the screed pad and the screed rail is pinch bolted to the screed post. The screed post height is then typically established by optical leveling procedures. The screed is then interfaced to the screed rail and subsequently drawn over the surface of the concrete pour.
In addition to the above-mentioned method, the screed rail may be secured through the use of a Nelson stud screed post assembly as described in Applicant's U.S. Pat. No. 5,212,919 of May 25, 1993. As such, the screed post assembly comprises a U-shaped bracket that is sized and configured to receive a screed rail. The bracket is attached to an elongate screed post that can interface with a Nelson stud. The screed post is configured to be coaxially alignable with the Nelson stud such that the post and bracket can be lowered upon the Nelson stud. The screed post and bracket are then supported by the Nelson stud at a location along the longitudinal axis of the support beam. The bracket attached to the screed post is configured to allow adjustment of the screed rail in a vertical direction in order to position the screed rail at the prescribed height above the metal decking.
As will be appreciated by those familiar with concrete construction techniques, drawing the screed over the poured concrete is very labor intensive. The concrete is poured onto the deck and the screed is manually drawn over the concrete by pulling the screed. The screed is difficult to pull due to the weight of the concrete that must be moved and the friction created between the tabs extending from the screed and the screed rails supporting such tabs. In forming thick decks, typically over 12 inches thick, there has been developed a vibrating screed in order to help move the vast quantities of concrete. The vibrating screed has a motor that vibrates the screed in order to help move and compact the concrete. However, the vibrating screed must still be manually pulled over the poured concrete. Drawing the screed over the concrete can lead to injuries to the concrete laborer due to the pulling he must perform to draw the screed over the un-level concrete pour.
The present invention addresses and overcomes the above-described deficiencies in prior art screeds by providing a screed that easily slides over the screed rails. In fact, the screed of the present invention is operable to vibrate and pull the screed over the concrete through the use of a motor. Therefore, the present invention provides a device that can easily move concrete without injury to the concrete laborer.